1. Field of Invention
This invention relates generally to medical devices, more particularly to devices for removal of stone, foreign bodies and the like from the body.
2. Discussion of Prior Art
Existing techniques for extraction of stones from the body such as in the case of stones lodged in the urinary collecting system and in the biliary tree can be cumbersome, inefficient and risky with respect to complications. For example, the extraction of urinary stones often requires cystoscopic balloon dilation of the distal ureter using a high pressure balloon to increase the capacity of the ureter in order to allow decreased resistance with passage of the ureteroscope and extraction of the stone or its fragments. This high pressure balloon requires a costly pressure gauge and can be traumatic to the ureter placing the ureter at risk for stricture formation. After dilation, an ureteroscope is inserted and lithotripsy performed if the stone is too large for extraction. The stone is then engaged under direct vision with a basket or similar device and then withdrawn into the bladder where the stone is then considered passed. This technique requires that the stone be of sufficiently diminutive size (which is usually not the case with a lodged stone) or that the stone be fragmented with a device such as a laser which in itself carries the risk of injury to the ureter. Furthermore, extraction of a stone engaged in a wire basket carries the risk of frictional damage to the ureteral mucosa and wall, the risk of a retained basket engaged with stone requiring tertiary referral or open surgery, or the risk of catastrophic avulsion injury of the ureter.
The above time consuming, costly and risky standard techniques begs for the development of a device which will provide a less cumbersome, safer, more efficient and less costly technique to treat the extremely common problem of urinary stone disease. Other inventors have attempted to address this vexing task.
Hardwick, U.S. Pat. No. 4,469,100, proposed a device in which the stone is drawn into the balloon by intussusception, protecting the ureteral walls from the friction with stone extraction. The deficiencies of this idea include the blind passage of the device to the stone (i.e.: not under direct visualization as with the standard technique), dependence upon suction to engage a stone which has an irregular surface not amenable to suction seal for traction, and, most significantly, the device's construction where the balloon is attached to the catheter near its proximal and distal ends. The result of the latter construction is that, while the stone achieves sanctuary within the confines of the balloon's wall during intussusception, the external surface of the balloon is withdrawn in direct opposition to the ureteral wall when extracting the stone which places the ureter at risk for injury.
Another inventor who attempts to solve the existing problems with stone extraction is Drettler, U.S. Pat. No. 4,927,426. Here a catheter-like device is used which allows a laser fiber for lithotripsy but suffers the same deficiencies as Hardwick's device. U.S. Pat. Nos. 4,243,040 and 4,295,464, likewise, suffer similar problems.
Current techniques for biliary stone extraction also can be cumbersome, inefficient and risky for complication. Gallstones may become lodged in the biliary tree, often at the sphincter of Oddi which may result in biliary colic and cholangitis or pancreatitis. Many surgical devices and techniques exist for treatment of these stones confined to the biliary tree and unable to pass to the duodenum. Access to and extraction of biliary stones often require balloon dilation or sphincterotomy at the duodenal papilla which carries the risk of bleeding and perforation. The stone is then engaged with a basket, such as Cook's The Web™ Extraction Basket which risks, as with a urinary stone, injury of the biliary ductal system and retention of the basket.
Another technique for stone extraction uses a balloon such as that described by Karpeil, et al., U.S. Pat. No. 6,692,484 B1, where the sphincter is dilated and a second balloon is used to push the stone through into the duodenum. Similar balloons, such as the Cook Endoscopy Tri-Ex® Triple Lumen Extraction Balloon, often requires sphincterotomy. These balloons in general work well but do not directly control the stone as with a basket which can sometimes leave the stone wedged between the balloon and ductal wall.
Whatever the precise merits, features, and advantages of the above cited references, none of them achieves or fulfills the purposes of the present invention.